Skip to main content

Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

See other formats

438                                ALASKAN GLACIER STUDIES
where the snow had melted away, the advancing ice was overriding young shrubs which had budded in the season of 1911. There seemed to be no tendency to break up the buried ice in the interior flat.
At the glacier margin a low terminal moraine was being pushed along in front of the glacier, the slope of which at the end is 30 to 35. That the forward movement was exceedingly slow was shown by the fact that this terminal moraine did not have the shape of a push moraine, as at Columbia Glacier, but resembled a talus. This was because a very small amount of outwash gravel was being ploughed up by the slowly-advancing ice compared with the larger amount of moraine which was sliding down from the surface of the glacier. The ice front was moderately crevassed, but the ice was rather dirty, basal ice with much detritus, which was being released by melting so that it was continually sliding down the ice front to the talus moraine. La places numerous ice blocks from crevassed pinnacles had rolled down the frontal slope of the glacier and lay on and in front of the terminal moraine.
Relation of Glacier to Railway. The advance of Grinnell Glacier, in 1910-1911, and possiblyl912, might conceivably block the Copper River and Northwestern Railway, if the movement should continue long enough to break up the stagnant outer ice mass of the forested terminal hill and cause it to become crevassed, even if the glacier did not advance further into the river. This would make it impossible to operate the upper 150 miles of the railroad, for the small Grinnell Glacier, located at the lower end of Abercrombie Rapids, holds the key to the railroad situation from this point northward, particularly as the eastern bank of the Copper River in this portion (PI. CLXV) is also a glacier, over which the building of a railroad would be very difficult' and would involve at least two expensive bridges. The Grinnell Glacier is small, however, and the interior flat of moderate size, so that it would take a rather strong advance to disturb conditions in the outer part of the glacier where the railway crosses it and where practically all the ice seems to have melted out from beneath the present railway grade, though present a score or so of feet from it.